I have three categories of student - men, children, and a teenage girl.

The men get themselves to the classroom in time for the lesson - ie. anything from 15 minutes early to 45 minutes late - and leave with a bundle of notes which they never look at again.

The children are dropped off by their fathers, and picked up again 90 minutes later. Like children everywhere, almost all have no interest in sitting in a classroom - especially as they spent all morning sitting in a state-run classroom.

The fathers are also like most fathers everywhere, in that they're pushy, opinionated, and want the teacher to focus exclusively on their beloved offspring, for extra time, at half the standard rate. Whether said offspring like it or not.

There are boys and girls among the children, and they spontaneously segregate themselves into opposite sides of the room, never communicating, and pretending the other side doesn't exist. The girls know more, the boys talk more.

Then there's one girl of fifteen. And although she goes to school, she's not allowed to come to our school. Why? Because hormones. Whose hormones, I'm not sure, but it's definitely because hormones.

Boys of sixteen, no problem - because...well, because boy hormones. Boys of sixteen mixing with boys of ten, no problem. But for a teenage girl, I have to be driven to her home, sit and talk for an hour with father in the next room, and then he drives me back.

Plenty of parents want me to teach their young children in their homes, but official school policy is to always refuse. Why? Because security.

Security of who, and against what, is not exactly clear. But as an excuse, this one's useful.